Pulleys

Purpose of Pulleys:

          Pulleys are used to transfer force or speed to turn another pulley connected by a belt. 

Exmaples of Pulleys:

          Flag poles, cranes, water pumps, air conditioners, automobile engines, sewing

machines.

How to Use Pulleys:

·        The pulley you turn (called the driver) causes the other pulley (called the follower) to turn also, because they are connected by a belt.  The driver and the follower turn in the same direction.

·        The driver and the follower turn in the opposite direction when connected by a crossed belt.

·        A small driver makes a large follower turn slower (referred to as gearing down), which decreases the speed of rotation but increases the force.

·        A large driver makes a small follower turn faster (refereed to as gearing up), which increases the speed of rotation but decreases the force.

·        A belt drive can be used to change the direction of rotation by 90 degrees.

·        A fixed pulley can change the direction of a lifting force to a more convenient angle. 

·        A moveable pulley can be used with a fixed pulley to lift a load with less effort than with a fixed pulley alone.

LEGO® DACTA, Teacher Guide 9624 Pulleys (1993)

Back to the Gears & Pulleys Lab or Contents